We have had to replace far too many hydraulic cylinders for tails in the past year. Boxes are jumping off the rails and damaging the cylinder and then it starts to leak. It only takes a little scratch on the cylinder and it will eventually damage the seal and start to leak. Its about $2,750.00 each time. Please be extra careful when pulling boxes at an angle or boxes that are not level. Don't be afraid to ask for help if you are worried you are going to damage something.